DETOXIFICATION OF METALS--IN VITRO AND IN VIVO STUDIES

描述：已知砷和其他有毒金属和类金属 被扔在了很多超级基金的地点两大生物 解毒金属离子的机制是蛋白质结合， 通过酶如甲基转移酶将它们甲基化，甲基转移酶使用S- 腺苷甲硫氨酸和/或维生素B12作为辅酶。这似乎是 砷硒和可能的铅都是如此的分子机制 甲基化通过什么途径完成是未知的。酶反应 砷酸盐/亚砷酸盐的生物转化是未知的。酶 用于砷酸盐/亚砷酸盐生物转化为更少的 有毒的甲基胂酸盐和毒性小得多的二甲基胂酸盐， 仅在有限程度上使用粗的、不纯的酶匀浆进行了研究 细菌、真菌或老鼠。也有有限的，在体内， 在实验动物和人类的代谢研究中， 给予化合物并鉴定尿液中的代谢物。这 该项目涉及人体酶的分离和纯化， 结合蛋白的解毒砷酸盐/亚砷酸盐，以研究 这些解毒作用的分子机制。这样，对于 第一次，解毒的酶机制， 砷化物/亚砷酸盐在人类中的作用将得到理解。一旦砷 生物转化酶已经被表征，其他金属离子如 如铅、硒、镉以及卤代芳香族化合物 碳氢化合物将被研究，看看他们是否抑制酶 砷的生物转化控制和管理这些 纯化的酶将被研究和抑制剂和刺激剂的 酶将被研究。用砷酸盐激发的动物的尿液将 测试甲基转移酶活性，以确定这些 酶可用作体内浓度的生物指示剂 有毒的活性砷挑战测试， 使用DMPS（2，3-二巯基丙烷-1-磺酸）测定人体中的砷 将被开发。这样的挑战测试将有助于 确定人类暴露于砷，并将有助于 确定超级基金地点附近人类的砷暴露。

Description: Arsenic and other toxic metals and metalloids are known to have been dumped at numerous superfund sites. Two important biological mechanisms for detoxifying metal ions are protein binding, and methylating them via enzymes such as methyl transferases which use S- adenosylmethionine and/or vitamin B12 as coenzymes. This appears to be true for arsenic, selenium and possibly lead. The molecular mechanisms by which methylations are accomplished are unknown. The enzyme reactions for the biotransformation of arsenate/arsenite are unknown. Enzyme reactions for the biotransformation of arsenate/arsenite to the less toxic methylarsonate and much less toxic dimethylarsinate have been studied only to a limited extent using crude, impure enzyme homogenates of bacteria, fungi or the rat. There have also been limited, in vivo, metabolic studies in experimental animals and humans in which arsenic compounds were given and the metabolites in the urine identified. This project deals with the isolation and purification of human enzymes and binding proteins that detoxify arsenate/arsenite in order to study the molecular mechanisms of these detoxifications. In this way, for the first time, the enzymatic mechanisms for the detoxification of arsenate/arsenite in humans will be understood. Once the arsenic biotransforming enzymes have been characterized, other metal ions such as lead, selenium, cadmium, as well as, halogenated aromatic hydrocarbons will be studied to see if they inhibit the enzymatic biotransformation of arsenic. The control and regulation of these purified enzymes will be studied and inhibitors and stimulators of the enzymes will be studied. Urine of animals challenged with arsenate will be tested for methyltransferase activities to determine whether these enzymes can be used as biological indicators of the body's concentration of toxicologically active forms of arsenic. A challenge test for arsenic in humans using DMPS (2,3- dimercaptopropane-1-sulfonic acid) will be developed. Such a challenge test will be helpful for determining the exposure of humans to arsenic and will be useful to determine arsenic exposure of humans near superfund sites.